Finding and Repairing Water Main Breaks

Water mains are the primary water supply line systems in cities, towns, and neighborhoods across the country. Water mains are used to transport water directly from the city treatment facility into neighborhoods and business districts.

Water mains are typically large diameter pipes made of plastic or metal that are part of a community’s water distribution system. If the water supply system can be imagined as a tree, individual businesses and homes will be the leaves, and water mains are the branches and the trunk.

The diameter of pipelines in a water main system typically ranges from 6 to 16 inches and they can be constructed of PVC, ceramic, steel, ductile iron, concrete, or asbestos. Water mains are generally installed deeply in the ground to prevent freezing and other damage.

What is a Water Main Break

A water main break occurs when a section of pipeline in the water supply system is damaged or broken. Water main breaks are often immediately detected due to a loss of water pressure across large sections of a water supply system. Modern water main systems are often installed in a grid pattern so that damaged sections can be isolated for repair while allowing the rest of the water supply system to continue to operate. This means that during a break, most customers are able to have water restored in a very short amount of time.

What Causes a Water Main Break

There are many causes of water main breaks. Below are some of the most common along with some prevention techniques:

• Freezing: When temperatures drop too low, the water in a pipeline can freeze. Unlike most materials, when water freezes it expands. The pressures on pipeline walls created by this expansion can be enormous, leading to cracked or broken pipelines. Prevention methods for freezing damage include leaving a small amount of water flowing in the line (such as by keeping a valve or a faucet slightly open), or by running heating elements along the pipeline. Alternatively, the deeper the pipeline is buried, the less like it is to freeze.
• Drought: soils, especially clays, can shrink when they dry. If large sections of soil shift too far, they can drag sections of pipeline with them leading to broken joints or cracking. Keeping soil moist, or burying pipelines below the drought-line can help prevent this damage.
• Tree Roots: Slow growing, but powerful, tree roots can break through concrete, asphalt, and rock. A plastic or metal pipeline stands no chance against a slowly expanding tree root. The best prevention method is to place pipelines away from large trees, or from trees that are likely to grow significantly in the future.
• Construction/Excavation: Responsible contractors call 811 or locate lines themselves before breaking ground. Unfortunately, mistakes can still occur. Usually, a contractor is immediately aware of the line strike and will take steps to get it repaired quickly. Utility locating equipment can be helpful in preventing line strikes and damage to water mains.
• Water Hammer: When valves are closed too quickly on a water main, the moving water can come to a swift stop. Water is very heavy and the momentum water needs to go somewhere. If there is too much momentum, the water may break through a valve or burst a pipeline joint. Water hammer can be prevented by gradually closing valves. There are also valves designed specifically for water hammer prevention.
• Municipal Work: Cities and towns are often the owners and operators of municipal water mains. These systems occasionally need upgrades or maintenance, and damage can occur to lines during this work.

How to Find a Water Main Break

A good indication of a water main break is a partial or complete loss of water pressure in a portion of a water supply system. If this occurs, a leak survey should be conducted to identify which part of the system the break is on.

If water is found to be pushing up through the surface of the ground, the break may be located nearby. However, water from a main break can travel long distances underground before finding a route to the surface. To save unnecessary digging, water service professionals should use a pinpointing device to confirm the leak location.

Water Leak Surveys

Water leak surveys are performed by utility professionals to determine which lines on their system are leaking. These are generally conducted on a street-by-street, or line-by-line basis. During these surveys, the ground microphone of an acoustic leak detector is put into direct contact with hydrants, valves, or pipelines.

Since solids such as metal or plastic conduct sound better than soils this direct connection is an effective way to listen for leaks along long stretches of pipeline. The connection is generally made with a contact rod threaded directly to the microphone, or with a powerful magnet that allows the microphone to attach to an iron or steel valve or hydrant.

Water Leak Pinpointing

Once a line has been identified with a suspected leak, the operator uses the leak detector’s microphone and walks the length of the leaking pipeline, placing the microphone on the ground every few feet. As the operator gets closer to the leak location, the leak noises become louder. After passing the leak location, the sound will begin to decrease.

Water Main Break Locating Equipment

A class of tools has been developed specifically for the water supply industry to identify which lines are leaking and to pinpoint the exact location of those leaks. These devices are known as acoustic leak detectors.

Acoustic leak detectors utilize sound waves for the detection of waterline breaks and leaks. Think of an acoustic leak detector as a “stethoscope” for listening to leaks in a water supply system.

These systems can save hours of unnecessary excavation and can allow repair crews to quickly and efficiently identify the precise location of a water main break.

How to Repair a Water Main Break

Repairs of water mains should only be conducted by water service professionals or licensed plumbers. Water supply pipelines can vary in construction materials and may be built of plastic, cast iron, ductile iron, ceramic, or cement. Lines in older parts of towns could even be constructed with asbestos. Needless to say, these lines could be dangerous as well as difficult to repair. If you have located a water main break, it is important to notify the manager of the pipe system immediately to prevent further damage and to allow repair assessments to begin.

Once professionals have located the water main break, repairs follow the general sequence below:

• The broken section of pipeline is isolated from the rest of the system. This allows the line to be drained and is usually done in a manner that minimizes water service disruption to as many customers as possible.
• The broken section of line is excavated. Usually, the soils around the break are sodden and waterlogged. Once the trench has been excavated and the pipeline is exposed, it is likely that pumps will need to be used to remove water from the trench.
• The break is identified, inspected, and repaired. If necessary, a complete section of pipeline may need to be replaced. This may also be a good time to perform upgrades to the pipeline system.
• Once repaired, pressure testing may be conducted to test the soundness of the repair.
• The repaired line is then cleaned and flushed. This is necessary since contaminants may have entered the system during the leak or during the repair work. Customers may be instructed to allow their faucets and lines to run for a prescribed amount of time to flush all a potentially contaminated water from their personal systems.
• The repair site is then restored. This can include reburial of the pipeline, rebuilding of sidewalks or streets, and planting of new grass.
• Testing should be conducted on the newly repaired line at regular intervals over the coming weeks to ensure that the repair is holding and that all contamination has been removed from the system.

Water Main Breaks for Non-Professionals

Water supply organizations are usually aware of water main breaks almost immediately. Most systems have pressure monitors throughout their system and operators are immediately notified of any pressure loss. If, however, you have lost water pressure to your home or business, it is still important to notify your water supplier as soon as you notice the loss of pressure. The pressure monitoring systems may not be functioning properly.

Alternatively, if the water supply company has not recorded a decrease in pressure on their systems, this may be a good indication that something is wrong with the supply line to your individual water system.

Additionally, water supply organizations need to know which consumers are affected by a break in order to provide appropriate notices for pipeline sanitation, flushing, and service restoration.

While waiting for your water mains to be repaired, it is important to ensure that you have access to a clean supply of drinking water. If the outage is large, or due to a significant natural disaster, it may be some time before the water supply is restored. It is important, however, to remember to not drink or bathe in municipally supplied water until you are informed by the water supply company that it safe to do so.

Breaks in a Water Main are not Forever

Access to clean water for drinking and bathing are necessities for modern life. When a water main breaks, it is generally considered an emergency and repairing the break quickly becomes a priority for water supply companies. If you have not received information on the status of the repair operations after 24 hours, contact your water supplier and they will generally be happy to provide you with an update.